Electrolytes for lithium sulfur cells

Abstract

Disclosed is an additive for an electrochemical cell wherein the additive includes an N—O bond. The additive is most preferably included in a nonaqueous electrolyte of the cell. Also disclosed are cells and batteries including the additive, and methods of charging the batteries and cells. An electrochemical cell including the additive preferably has an anode that includes lithium and a cathode including an electroactive sulfur-containing material.

The invention claimed is: 
     
       1. An electrochemical cell comprising:
 (a) a cathode comprising an electroactive sulfur-containing material; 
 (b) an anode comprising lithium; and 
 (c) a nonaqueous electrolyte, wherein the electrolyte comprises:
 (i) one or more nonaqueous solvents selected from the group consisting of acyclic ethers, cyclic ethers, polyethers, cyclic acetals, acyclic acetals and sulfones; 
 (ii) one or more lithium salts; and 
 (iii) one or more N—O additives, 
 
 wherein the one or more N—O additives is selected from one or more of the groups consisting of nitramines, isonitramines, nitramine salts and isonitramine salts. 
 
     
     
       2. The cell of  claim 1  wherein the concentration of the one or more N—O additives in the electrolyte is from about 0.1 m to 1.5 m. 
     
     
       3. The cell of  claim 1  wherein the concentration of the one or more N—O additives in the electrolyte is from about 0.2 m to 1.0 m. 
     
     
       4. The cell of  claim 1  wherein the concentration of the one or more lithium salts in the electrolyte is from about 0.2 m to about 2.0 m. 
     
     
       5. The cell of  claim 1  that further includes a separator disposed between the anode and the cathode. 
     
     
       6. The cell of  claim 5  wherein the one or more N—O additives was included as part of the separator and was introduced into the electrolyte after the electrolyte came into contact with the separator. 
     
     
       7. The cell of  claim 1 , wherein the isonitramine salts are selected from one or more of N-Nitroso-N-phenylhydroxylamine ammonium salt (cupferron) and N-Nitroso-N-phenylhydroxylamine alkali metal or substituted quaternary ammonium salt. 
     
     
       8. The cell of  claim 1  wherein the nonaqueous solvent comprises cyclic acetals with the structure: 
       
         
           
           
               
               
           
         
       
       where R 1 , R 2 , R 3  and R 4  are organic radicals or H, and n is equal to or larger than 2. 
     
     
       9. The cell of  claim 1  wherein the nonaqueous solvent comprises acyclic acetals with the structure: 
       
         
           
           
               
               
           
         
       
       where R 1  and R 2  are organic radicals or H, and R 3  and R 4  are organic radicals. 
     
     
       10. A battery comprising a casing and one or more cells of  claim 1 .